Oxygen is a high value commodity chemical, with demand for tonnage quantities increasing due to a steady growth in process operations such as oxyfuel combustion and oxygen-blown gasification. Typically oxygen is generated via separation from air using cryogenic and non-cryogenic distillation. Cryogenic distillation methods are often utilized for applications that require high quantities of oxygen at low temperatures, while non-cryogenic separations typically involve the separation of air at ambient temperatures using either molecular sieve adsorbents via pressure swing adsorption (PSA), or membrane separation process using polymeric membranes. There are also air separation techniques using chemical processes based on absorption and desorption of oxygen at particular pressure and temperature conditions.
Oxygen has also been separated from air using by utilizing the difference in magnetic susceptibility between oxygen and nitrogen in processes generally referred to as magnetic separation. Oxygen is strongly parametric, and this has been exploited in a variety of configurations. In some methodologies, high gradient magnetic fields near the surfaces of magnetized wires have been utilized to capture oxygen molecules. In other methodologies, opposite magnetizing forces act on paramagnetic oxygen atoms and diamagnetic nitrogen atoms to separate trajectories. See e.g. U.S. patent application Ser. No. 13/691,723 by Raizen et al., filed Nov. 30, 2013 and published Jul. 11, 2013. The first method cannot enrich oxygen continuously because the magnetized wires have a saturation phenomenon to capture oxygen molecules, and the latter is strongly influenced by the gas turbulence and the molecular diffusion that results in the remixing of oxygen and nitrogen. Other approaches have utilized a “magnetic sieve” approach in order to continuously divert oxygen and nitrogen into separate streams. See Zhang et al., “Effect of magnetic yoke on magnetic field distribution and intercepting effect of multichannel cascading magnet arrays,” AIP Conf. Proc. 1207 (2010); see also Wang et al., “A Novel Magnetic Separation Oxygen-enriched Method and the influence of Temperature and Magnetic Field on Enrichment,” Journal of Thermal Science 16 (2007). Other approaches have utilized substantially porous materials through supporting materials which generate magnetic flux generally parallel to the pressure gradient of a flow in order to repel nitrogen while generally attracting oxygen into the pores. See e.g. Ciesla et al., “Theoretical consideration for oxygen enrichment from air using high-TC superconducting membrane,” PRZEGLD ELEKTROTECHNICZNY (Electrical Review), R. 88 NR 7b (2012); and see U.S. Pat. No. 4,704,139 issued to Yamamoto et al, issued Nov. 3, 1987; and see U.S. Pat. No. 5,779,770 issued to Nitta et al., issued Jul. 14, 1998. These methodologies generally proscribe the presence of magnetic material over substantially all of the resulting devices, and typically generate a magnetic field expected to operate with a generally perpendicular orientation over the entirely of the device, regardless of pore location.
Provided here is a mechanical membrane for the separation of a paramagnetic component which utilizes a plurality of pores extending through a supporting material, with each pore surrounded by a plurality of magnetic regions arranged to optimize a magnetic field in the locality of an individual pore. The magnetic regions around a given pore are arranged to augment the magnetic field on one side of the supporting material while mitigating the field to near zero on the opposite side, in order to minimize the magnetic material required. In operation, a flow of fluid such as air comprising a paramagnetic component such as O2 is directed toward the mechanical membrane, and the paramagnetic component is typically attracted toward a magnetic field surrounding a pore while diamagnetic components such as N2 are generally repelled. Such an apparatus and method may be utilized for the magnetic separation of paramagnetic components from a mixture in a variety of environments and applications requiring tonnage quantities of oxygen.
These and other objects, aspects, and advantages of the present disclosure will become better understood with reference to the accompanying description and claims.